Saturday, November 6, 2010

Astronomical Analysis of Iedl Adha 1431-H

On 16 November 2010, insya Allah, Muslim in Asian region will celebrate the sacrificing day, Iedl Adha 1431-H. Unfortunately though, unlike the Iedl Fitri 1431-H, the crescent (hilal) altitude to mark the beginning of Dzul Hijjah 1431-H that will be coincident with the sunset of 6 November 2010 will be rather low. Although the conjunction (this marks the zero point of a lunar month) will occur at 11:54 western Indonesian time, the altitude of the crescent will be only about 1.6 degrees when the sun sets in the western local horizon of Jakarta on 6 November 2010.

In many occasions, Muslims who follow madzhab (school of thought) that the crescent should be visible to human eyes, will invalidate it as the beginning of any Muslim month, as they put a prerequisite that the crescent altitude must be minimum of 2 degrees. Instead, they will postpone the beginning of Dzul Hijjah 1431-H to the next day, 7 November 2010.

As Iedl Adha will be on the tenth day of Dzul Hijjah, it is very likely there will be disagreement in the procession of Iedl Adha prayer for Muslims in Asian region. Some will conduct the prayer on 16 November, but the other half would organize it on the 17 November.

If you are interested in understanding the astronomical characteristics of the crescent and the sun in November 2010, you might need to download the following file:, or just click this DOWNLOAD. It is basically a power point simulation for the crescent and the sun characteristics between 5-22 November 2010.

The English version can be downloaded from the following link: or simply click this DOWNLOAD ENGLISH VERSION.

Tono Saksono